A plane is escorted by a law enforcement vehicle to a terminal at Philadelphia International Airport in Philadelphia, Thursday, Jan. 21, 2010. A spokesman for US Airways says a flight from New York to Louisville, Ky., has been diverted to Philadelphia International Airport because of security concerns. (AP Photo/Matt Rourke)

Philadelphia (AP) - A misunderstanding about an Orthodox Jewish prayer ritual led a US Airways Express captain to divert his Kentucky-bound plane to Philadelphia on Thursday, authorities said.

A 17-year-old boy on Flight 3079 traveling from New York to Louisville was using tefillin, a set of small black boxes attached to leather straps and containing biblical passages, said Philadelphia police Lt. Frank Vanore.

When used in prayer, one box is strapped to the arm while the other box is placed on the head.

"It's something that the average person is not going to see very often, if ever," FBI spokesman J.J. Klaver said.

The teen explained the ritual after being questioned by crew members, but the captain decided to land in Philadelphia anyway, authorities said.

The flight left LaGuardia Airport in New York around 7:30 a.m.; it landed without incident in Philadelphia about 90 minutes later and was met by police and officials from the FBI and Transportation Security Administration.

Authorities said the plane was searched and passengers were questioned. The teen, who is from White Plains, N.Y., and was traveling with his 16-year-old sister, was very cooperative, Vanore said.

"They were more alarmed than we were," Vanore said.

Klaver said the teen and his sister were never in custody, and have been cleared to continue their travels.

Passengers on 50-seat regional jet, which was operated by Chautauqua Airlines, were rebooked on other flights, US Airways spokesman Morgan Durrant said.

A misunderstanding about an Orthodox Jewish prayer ritual led a US Airways Express captain to divert his Kentucky-bound plane to Philadelphia on Thursday, authorities said.